Cold-drawing steel wire



Patented Dec. 26, 1950 T :i

uu rso STATES PATENT OFFICE 7 2,535,284 i :COLDJ- DBAWING STEEL WIREArch. W. Harris, Euclid, Ohio, ass'ignor to The American Steeland WireCompany of ,New Jersey, a corporation of New Jersey Nolnrawing..Application SeptemberBO, 1947,

' Serial No. 777,119

This invention relates to cold-drawing steel wire and more particularlyto the preparation of steel wire and the surface thereof for drawing.

Steel wire is conventionally given a so-called patent anneal at anintermediate stage in its manufacture in order to impart the desiredphysical properties thereto and to toughen it sufficiently to withstanddrastic reductions effected by cold drawing. It is necessary in thispractice to acid clean the wire after the anneal to remove the scaletherefrom since it is harmful to the dies. Following cleaning, the wireis lime coated and baked to remove embrittlement resulting from the acidcleaning.

Accordingly, it is an object of this invention to overcome the foregoingdisadvantages to provide an improved method of preparing wire for colddrawing.

It is a further object to produce cold drawn wire in an efficient andeconomical manner.

In accordance with the teachings of my invention, high carbon steel wirecontaining between .50 and 1.00% carbon, .60 and 1.25% manganese andother elements in the usual residual amounts present in plain carbonsteel wire is produced by conventional steel making and drawingpractice. In order to prepare the wire for cold drawing and, in the caseof wire drawn to a size approaching that desired in the final product,to improve the final physical properties, the wire is patent annealed.This essentially comprises heating the wire to above its transformationtemperature followed by quenching it. This strengthens and toughens thewire to withstand drastic cold reductions. By my improved method, thewire is patent annealed by continuously heating it in a nonoxidizingatmosphere to a temperature between 1450 and 1900 F. The nonoxidizingatmosphere may be any inert gases such as nitrogen, helium and argon orreducing gases such as cracked ammonia, etc. The wire being annealedwill have a clean scale-free surface due to prior cold drawings but mayhave a slight amount of drawing lubricant thereon. This however willburn off without affecting the wire surface so that due to thenonoxidizing atmosphere, the wire will retain its bright cold drawnsurface.

After heating and without exposure to any oxidizing influences, the wireis immediately quenched in a lead bath, which according to the teachingsof my invention is maintained at a temperature between 800 and 1100 F. Ihave found that molten lead will begin to dissolve the lead oxide whichforms on the surface of the 2 molten lead at about 800 F. Ifbright-surfaced steel is introduced into molten lead maintained abovesuch temperature whereby it contains dissolved lead oxide, a chemicalreplacement occurs in accordance with the following reaction:

Thus the annealed steel wire having a clean surface resulting fromtreating in the foregoing manner will receive a very thin oxide filmwhich is substantially all ferrous oxide (FeO) during its passagethrough the lead bath.

The wire with this film of oxide thereon may be cold drawn with improvedresults as compared to the conventional practice of removing scale,applying a lubricant and then drawing. However, if desired, the wirewith the film of oxide may be coated with any conventional coatings suchas silicates, borates, phosphates, soaps, alkalies or mixtures thereof.The prime purpose of such coatings is to prevent rusting or formation ofhigher iron oxides on the surface of the wire prior to cold drawing itand thus retain the film of ferrous oxide thereon.

While I have shown several specific embodiments of my invention, it willbe understood that these embodiments are merely for the purpose ofdescription and that various other forms may be devised within the scopeof my invention, as defined in the appended claims.

I claim:

1. A method of preparing wire for cold drawing, comprising annealingsubstantially scalefree wire in a nonoxidizing atmosphere and withoutexposure to oxidizing influences quenching said annealed wire in a leadbath containing lead oxide to produce a film of ferrous oxide thereon.

2. A method of preparing high carbon steel wire for cold drawing,comprising annealing substantially scale-free wire in a nonoxidizingatmosphere and without exposure to oxidizing infiuences quenching saidwire in a lead bath containing lead oxide to produce a thin film offerrous oxide thereon.

3. A method of preparing carbon steel wire for cold drawing, comprisingannealing substantially scale-free wire in a reducing atmosphere at atemperature between 1450" and 1900 F. and without exposure to oxidizinginfluences im mediately quenching the same in a lead bath containinglead oxide maintained at a temperature between 800 and 1100 F. toproduce a ferrous oxide film thereon.

4. A method of cold-drawing steel wire c0m- 3 prising annealingsubstantially scale-free wire in a reducing atmosphere at a temperaturebetween 1450 and 1900 F. and then without exposure to oxidizinginfluences immediately quenching the annealed wire in a lead bathcontaining lead oxide maintained at a temperature between 800 and 1100F. to produce a film of ferrous oxide thereon and cold drawing the wirewith said oxide film thereon.

5. A method of drawing high carbon steel wire comprising annealingsubstantially scale-free wire in a reducing atmosphere at a temperaturebetween 1450 and 1900 F. and then without exposing the wire to oxidizinginfluences immediately quenching it in a lead bath containing lead oxidemaintained at a temperature between 800 and 1100 F. to produce a film offerrous oxide thereon, coating said ferrous oxide coating with 4 anoxidation resistant material and drawing the wire with the ferrous oxidefilm thereon.

ARCH W. HARRIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS m Number Name Date 279,295 Watson et al June 12,1883 2,369,805 Schultz Feb. 20, 1945 FOREIGN PATENTS 15 Number CountryDate 511,628 France Sept. 27, 1920 249,649 Italy- Aug. 4, 1926

4. A METHOD OF COLD-DRAWING STEEL WIRE COMPRISING ANNEALINGSUBSTANTIALLY SCALE-FREE WIRE IN A REDUCING ATMOSPHERE AT A TEMPERATUREBETWEEN 1450* AND 1900*F. AND THEN WITHOUT EXPOSURE TO OXIDIZINGINFLUENCES IMMEDIATELY QUENCHING THE ANNEALED WIRE IN A LEAD BATHCONTAINING LEAD OXIDE MAINTAINED AT A TEMPERATURE BETWEEN 800* AND1100*F. TO PRODUCE A FILM OF FERROUS OXIDE THEREON AND COLD DRAWING THEWIRE WITH SAID OXIDE FILM THEREON.